Tissue specific expression and chromosomal mapping of a human UDP-N-acetylglucosamine :alpha 1,3-D-mannoside beta 1,4-N-acetylglucosaminyltransferase

A human cDNA for UDP-N-acetylglucosamine:alpha 1,3-D-mannoside beta 1,4-N-a cetylglucosaminyltransferase (GnT-IV) was isolated from a liver cDNA librar y using a probe based on a partial cDNA sequence of the bovine GnT-IV, The cDNA encoded a complete sequence of a type II membrane protein of 535 amino acids which is 96% identical to the bovine GnT-IV, Transient expression of the human cDNA in COS7 cells increased total cellular GnT-IV activity 25-f old, demonstrating that this cDNA encodes a functional human GnT-IV, Northe rn blot analysis of normal tissues indicated that at least five different s izes of mRNA (9.7, 7.6, 5.1, 3.8, and 2.4 kb) for GnT-IV are expressed in v ivo. Furthermore, these mRNAs are expressed at different levels between tis sues. Large amounts of mRNA were detected in tissues harboring T lineage ce lls. Also, the promyelocytic leukemia cell line HL-60 and the lymphoblastic leukemia cell line MOLT-4 revealed abundant mRNA, Lastly, the gene was map ped at the locus on human chromosome 2, band q12 by fluorescent in situ hyb ridization.